Hammer mill feed end



March 21, 1944. J BRlED 2,344,591

HAMMERMILL FEED END Filed Dec; 31, 1940 INVENTOR.

Patented Mar. 21, 1944 HAMMER MILL FEED END Julien A. Bried, Berkeley,

terprise Engine & Foundry Company, San

Francisco, Calif., a corp Calif., assignor to Enoration of California Application December 31, 1940, Serial No. 372,617

3 Claims.

This invention relates to vertical hammermills or disintegrators of the type in which the material to be disintegrated is introduced at the upper end of the rotor chamber and the high speed revolving hammers or beater arms projecting from the rotor shaft forcibly strike the material and reduce it to the desired degree of fineness, and after which the disintegrated material is discharged from the mill.

The principal object of the invention is to provide improvements to the feed end of such mills whereby the accidental entry of stray pieces of iron, or other metals or unbreakable materials is to a great extent avoided. Other objects and advantages of the invention will appear in the following description and accompanying drawing.

In the drawing the figure is a vertical sectional view of a conventional type of verticalhammermill shown with my improved features incorporated into the feed end of the mill.

The usual well known features of the mill comprise a frame I having an outwardly-projecting base flange for mounting on a foundation, while at the upper end is a spacing frame 4 in turn supporting a motor 5, the shaft of which is extended or coupled to the rotor shaft 8 of the m1 The rotor shaft extends downwardly through a cylindrical chamber formed by curved screen sections or shell 9 and the shaft is rotatably positioned in bearings l and H, the latter of which receives and supports the lower end of the shaft. Spaced outwardly from the cylindrical screen is a circular outer casing I! as of curved sheet metal sections suitably clamped together as by clamp bolts l8.

Within the screen space the shaft 8 is provided with the usual beater arms or so-called hammers 20 which project from the shaft, or rather from a hub or hub sections 2| suitably secured to the shaft, and which beater arms may be of any size, shape, or length, fixed or pivotally mounted, and in any desired arrangement, as commonly used in mills of this type for beating and disintegrating material fed into the upper end of the rotor space for passage of the disintegrated materials through the screen if a screen is used, or passing straight through the rotor space for discharge if the screen shell be imperforate, or in both directions if the screen is used and the lower end of the rotor space is left open as indicated in the drawing, and in which latter case the treated materials emerge in direction indicated by the arrows, all as old and well known in the art.

The improvement herein concerned has to do,

as stated, with the feed end of the mill, and comprises the provision of a downwardly slanted feed chute 22 which enters one side of the elongated cylindrical upper portion I of the mill and is formed or connected with a vertically positioned cylindrical portion 23 which is mounted above the rotor space and is of smaller diameter than the main beater arms 20 and within which smaller cylinder are a few shorter beater arms 24 also secured to the shaft 8 but which manifestly will have a much lower peripheral speed of travel than the longer arms 20..

Cylindrical part 23 is preferably fiangedfoutward as at 23' to restupon-the upper edge of a pre-breaker ring 25 within which some short beater arms 26 revolve, the feature of the prebreaker ring and short arms within being old in the art, while at one side of member 23 is an opening across .which is bolted or otherwise secured a laterally extending neck 2? turned downwardly at itsouter end and provided with a normally spring closed trap door 28. Withinthe neck 27 is another normally closed trap door 29 to cover the opening in the wall of cylindrical member 23 and which door 29 may be of rubber closed by its own resiliency and only opened upon impact from some heavy article thrown against it by the short hammers 2d.

The feed chute 22 is formed with an opening in its under side which opens into a downwardly directed discharge chute 30 also provided at its lower end with a normally spring closed trap door 3|, while extending substantially horizontally across the chute space of chute 22 is a screen plate 32 pivoted at its inner end at 33 and suspended at its forward end by one or more cords or chains passing upward over pulleys 34 and downward again with counterweights 35 attached at the end, all so that if any unduly heavy material should gather upon screen plate 32 to overcome the weight or weights 35, the plate 32 will swing downward along the dotted arc to the bottom of chute 30 and drop such heavy material into chute 3G for discharge therefrom at such time as when its spring closed door 3| becomes overloaded.

When the pivotally mounted screen plate 32 is relieved of its load, it is at once returned to the full-lined position of the drawing. The screen openings in plate or sheet of foraminous material 32 are large enough to pass the largest pieces of feed material intended for the mill, so that any unduly long pieces, such as an iron bolt or other unusual object will be stopped by the screen for automatic discharge when sufficient weight builds up, but to prevent some of the regular feed material from falling into chute 30 after passing through the screen 32 I provide a plate or panel 36 hinged at its upper end to the screen 32 at 31 and with its lower end free and which normally covers the opening to chute 3!] from the feed chute 22 as shown in section in the drawing, yet permits the screen to swing downward as described, as the panel being hinged to the screen at its upper and only at 31 folds down under the screen 32 when this swings down, all as indicated by the dotted position.

As some pieces of foreign material such as iron nuts and other small pieces of metal may pass through screen 32 they will be first struck by the shorter hammers 24 and due to their excessive weight will be hurled through the door 29 to lodge in neck 21 upon door 28 and will open the latter for automatic discharge when the accumulation is sufficient.

The spring or resilient closing efiect of door 29 must be such as will not open from the action of the normal feed particles when thrown against it. If any heavier pieces of ungrindable material are thrown over the cylindrical or tubular part 23 they will lodge within the space above flange 23 and may be removed through a hand-hole door 38.

With a vertical hammermill feed as above described, very little if any stray metal of a size which might injure the mill will ever gain access to the main beater arms 20.

Having thus described my improved construction, what I claim is: 1

1. In a hammermill having a vertically disposed revolvable shaft with hammers projecting therefrom forming a disintegrating rotor and operating within a cylindrical shell surrounding the hammers, and with an inclined feed chute extending downwardly from without at one side of and into the mill for guiding material to be disintegrated to the upper end of the rotor, the improvement which comprises providing a screen extending across the space within the feed chute in a manner to stop and hold thereon oversize pieces of material in the feed, means pivotally mounting said screen for swinging downwardly at an angle to drop off said over-' tion after dumping its load.

2. In a hammermill having a vertically disposed shaft with hammers projecting therefrom forming a disintegrating rotor and operating within a cylindrical shell surrounding the hammers and with an inclined feed chute extending downwardly from without at one side of and into the mill for guiding material to be disintegrated to the upper end of the rotor, the improvement which comprises providing an opening in the bottom of said feed chute embraced below by an outwardly extending discharge chute, a substantially horizontally disposed screen extendin across the space within said feed chute at a point above said opening in a manner to stop and retain upon it any oversize pieces of material in the feed, means pivotally supporting said screen for tilting downwardly to discharge any accumulated material through said opening into said discharge chute, and means counterbalancing said screen against such tilting movement until a predetermined load has accumulated upon it, the counterbalancing means automatically returning said screen to initial position after dumping its load. 7

3. In the construction set out in claim 2 a movable panel normally covering said opening in the bottom of the feed chute and means connecting said panel and screen in a manner whereby the downward tilting of said screen will move the panel from the opening and vice versa.

JULIEN A. BRIED. 

